This game was played on chess cube a few days ago with a 2+12 time control. Playing a hybrid Marshall Defense with the Black pieces, I lost some material in the opening through carelessness. My saving grace was a focus upon rapid development. The fourteenth move was a critical juncture. See whether you can find the winning move. I have placed the continuation at the bottom of this message.

The main strategic error of my opponent was to neglect development in favor of pawn-grabbing with the Queen. Castling Queenside was counter-productive as well, and I'm not sure it is possible to pull off such a brazen move in this position. I think he would have won based upon his material advantage if he had not played O-O-O or cxd, but instead a simple g3 to develop the King's bishop and prepare castling Kingside.